Method for making glass paper



Nov. 10, 1953 D. LABINO METHOD FOR MAKING GLASS PAPER Filed Nov. 17,1951 FIG-3 INVENTOR DoMlNlcK LABINO |3Y'7mm if A'rToRNEYs Patented Nov.10, 1953 METHOD FOR MAKING GLASS PAPER Dominick Labino, Waterville,Ohio, assignor to Glass Fibers, of Ohio Inc., Toledo, Ohio, acorporation Application November 17, 1951, Serial No. 256,930

2 Claims.

This invention relates to methods 'and apparatus for producing as a newarticle Aof manufacture a glass paper.

Paper consisting of glass fiber has heretofore been unknown in the art.Attempts made to produce glass paper have resulted in failure except asdisclosedin my co-pending application 247,010, filed September 17, 1951,because of the lack of any tensile strength in the material producedwhich rendered it useless as a paper in the many uses to which paper isadapted. Further, the material produced lacked surface finish andhardness, making it unsuitable for use aS paper.

However, I have discovered that fine glass fibers of uniform diameter,on the order of one micron and less, mat or felt together withself-adhesion to an extent that good tensile 'strength is imparted tothe product produced 'and that a smooth, hard surface finish can begiven to the material, thereby making it satisfactory for use as paper.With the glass fibers having uniformity of diameter and uniformity oflength, extreme uniformity of the paper is obtained.

Paper made of glass fibers vaccording to this invention hascharacteristics that are not capable of reproduction in papers made.from natural fibers, thus making glass paper adaptable for specialpurpose applications in which papers made from natural fibers cannot beused. For example, electronic components in which insulating papers areused are limited to a top temperature value of about 85 C., principallybecause of the destruction of the paper base of the component underheat. Thus, a paper made of glass fibers will permit of highertemperature elevation of electronic components because the :basic fiberdoes not deteriorate at low temperature- Gla'ss paper also has a verylow coefficient of expansion which eliminates diiculties resulting fromexpansion and contraction and since the glass fibers arenon-hydroscopic, there is no change in dimensional size resulting fromchanges in moisture content of the paper. These characteristics areuseful in the printing industry. Also, with the glass paper having ahard smooth surface, it is capable of receiving writing and printing.

Attempts at making papers yfrom vother synthetic fibers have resulted inproducts -unsuitable for many uses to which paper is adapted as thesynthetic fibers have required bonding, either by plasticizing thefibers slightly, or bonding has been obtained by the use of syntheticbinders.

2 Papers of this nature, however, are still highly susceptible todeterioration by heat or the bonding agent introduces a foreignsubstance into the paper which is subject to deterioration or makes itundesirable for use in special applications. The 'bonding together ofsmooth surfaced synthetic fibers has, therefore, been a substantialproblem in any attempt to produce a true paper from fibers other thannatural fibers.

It has been discovered, however, that Whenhibit felting or mattingcharacteristics and characteristics of surface adhesion that result in aphysical interlocking of the fibers together to an extent that a mattedor felted web of such glass fibers exhibits substantial tensilestrength. This is probably brought about because of the great surfacearea to weight ratio of the extremely fine glass fibers. The surfacearea of such fine fibers in a Web of any density is so great that thereis an actual surface adhesion between the fibers. Also, this result isoccasioned because of the diameter to length ratio of the fibers whereinthe length of the fiber is 500 to 1000 times the diameter resulting inextremey flexibility of the fiber which permits it to mechanicallyinterlock with the other fibers of like diameter and length.

Also, unlike natural fibers, glass fibers, when properly manufactured,are given the characteristics of" uniform diameter and substantiallyuniform length. Thus a paper made from glass 'ber of uniform diameter,and if desired, of uniform length, exhibits uniform physical, electricaland chemical characteristics as distinguished from non-uniformcharacteristics Aof paper made from natural fibers because of thevarying diameter and length of the natural fibers.

It is, therefore, an object of this invention to provide a method andapparatus for producing paper from glass fibers, and particularly toproduce paper having good tensile strength and which Iwill have uniformphysical, electrical and chemical characteristics.

It is another object of the invention to provide a method and apparatusvfor producing glass Glass bers having a diameter ofvone micron or lesswhen incorporated into a paper exhibit the characteristic ofself-adhesion, even though the surface of the glass fibers is entirelysmooth, resulting in a glass paper having substantial tensile strength.This self-adhesion of the glass fibers is occasioned merely by wettingthe Vfiber with water and collecting the wet fiber as a Web or sheet, orthe fiber can be collected in dry form and thereafter wet with water. Nobinder whatever is necessary to secure the self-adhesion of the glassfibers. A paper made from water Wet fibers exhibits good tensilestrength and uniformity of structure.

The self-adhesion is greatly increased by Wetting the fiber with an acidwater. It has been discovered that each glass of a different glasscomposition and a different alkaline content has a critical pHl value ofthe Water with which it Works best. The effect of the correct pH valueof the water made acid by any of the common acids, such as hydrochloricand sulphuric for example, is that of obtaining a much greater and amore even dispersion of the glass fiber in the water. The effect is muchthe same as would be occasioned by the use of a greatly increasedquantity of water to disperse the same amount of glass fiber. Also, amore uniform dispersion is obtained to an extent that less bunching ofthe fibers occurs in the water and the fibers seem to repel one anotherwhereby each fiber is separately dispersed in the water.

It has been discovered that as the alkaline content of the glass islowered, the acidity of the water in which the glass is dispersed mustbe increased. Fibers made from a high alkaline glass disperse readily inan acid water having a pH value of about 6.0, whereas the fiber madefrom a low alkaline glass disperses in the water only7 when the pH valueof the water is reduced to a value in the neighborhood of 2.0. Thus theacid content of the water is inversely proportional to the alkalinecontent of the glass, all as more fully disclosed and described in myco-pending application Serial Number 247,010.

To obtain glass fibers of a uniform diameter of one micron or less andretain the diameter of the fibers within a range of I-.45 micron, theconditions under which the glass fibers are produced are critical to theextent that conditions once established must thereafter be maintainedconstant to hold the sub-micron diameter of the fiber constant. Theglass fiber is of the class known as staple fiber, but the diameter tolength ratio is exceedingly high with the sub-micron diameter of thefiber providing for extreme flexibility and mechanical strength of thefiber.

In Figures 1, 2 and 3 there is illustrated an vapparatus for obtainingglass fibers of one micron in diameter or less and for producing paperfrom such ber. In Figure 1 there is illustrated a heating and meltingchamber I0 into which glass marbles are fed from a supply hopper II. Theglass marbles are fed into the heating and melting chamber I0 atperiodic intervals governed by the rate of removal of glass from theheating and melting chamber. Since the marbles are approximately 1/2" indiameter and the heating and melting. chamber I0 is approximately 5" indiameter, with the molten glass mass about 2.5 deep, the level of moltenglass in the heating and melting chamber is maintained at a constantlevel since the small amount of glass added by the dropping of a marbleintoV the body of molten glass in the heating and melting chamber is 6insufficient to cause any noticeable effect on'the level of the moltenglass in view of the small volume of the marble relative to the volumeof the molten glass in the heating and melting chamber. The heating andmelting chamber I0 is more particularly illustrated in Figure2 whereinit ltrated in Figure 3. A heating coil I5 is placed around the exteriorof the chamber I2 and is adapted for connection to a source of highfrequency energy which may, for example, be an electronic high frequencyoscillator, or a high frequency generator. 'I'he heating vcoil I5 isplaced substantially at. theglass melting level of the molten glass inthe chamber I2 to eect uniform heating conditions throughout the body of.the molten glass in the heating chamber or pot I0. The heating chamberI2 is preferably surrounded with a ceramic heat insulating ma,- terialI6 to conserve heat therein. Y

It has been determinedv over a long period of experimentation andmanufacture of glass fibers that the heating of glass by the use of ahigh frequency current in a heatingcoil that is placed around a circularheating chamber and positioned uniformly around the chamber results inobtaining absolute uniformity of viscosity of the molten glassthroughout vits entire mass within the heating chamber.

With the levely of the molten glass maintained constant within theheating chamber I2 and with the viscosity of the molten glass absolutelyuni.- form throughout the entire mass thereof, there is effectedidentically the same head of glass above each opening I4 in the bottomwall of the heating chamber I2 at a viscosity of exactly the .same asthat which occurs in the head of glass above every other opening in thebottom wall of the heating chamber. The head of glass aboveeach of the`openings is exactly the same because of the parallel placement of thebottom Wall of the heating chamber relative to the level of molten glasstherein. As a result, exactly the same quantity of molten glass isexuded through each of the openings I4 from the heating chamber I2.

The head of glass above the openings .I4 establishes a uniform pressuredifferential :between opposite sides of the body of the glass to causethe glass to exude through each of the openings at a constant rate inconstant volume. However, a positive pressure can be established abovethe body of molten glass in the chamber I2 should it be desirable toobtain a flow rate of the molten glass through the openings I 4 greaterthan that occasioned by the normal head.

The -streams of molten glass from the chamber I2 cool quickly so thatsolidified glass fibers can be passed between the drawing rolls I'I andI8 for drawing of the molten glass as it leaves the chamber I2 into thefine fibers that pass between the drawing rolls I1 and I8. The glassfibers I9 pass over a guide 20 having a recess to receive each of thefibers whereby the fibers are arranged in planar relationship for entryto between the drawing rolls I1 and I8. The drawing are preferably nf a.rubber-like material so :Irictionally .engage the glass bers l5 wherebyin phil them downwardly :from the heating `elzmzn'ilier l2.

mbe adrawing rolls if! EIB fare rdriyen by a amedhamieall .apparatus torotate them at constant .speed which is `controlled to establish :thediameter of the drawn Aglass ber ald hat e. predetermined and fixedwallie, tor exemple, M itoii inch.

With :tiene flow of :molten glass :from the heatchamber J2 heme at alcontrolled nare ,from :each lof the openings i4, eend ,the drawing:rolls al1 :sind 18;-sim1-1ltaneous1ydraw ing :esdh :of the moltenstrands into .glass ber ximm molten glass :of exactly the seme viscositydimming .at exactly the ssame rate, the drawn idirof nach nf the primary:glass ,fibers Id will be .exactly ithe same kWith-in ibut Mery minor:limits of 01x65 inch.

mbe primary :glass bers |29 .are advanced :by mbe drawing rolls l1 .and.Ix lover @the :dat state tfl mf .a ignide block 22 having :a`tl-,shaped 4edge an ,some1 alignment 'wim the weisses;

edge :23, `there iis mrovided .a igas hunner 24 that ibas fa 'zbonznntaldischarge :slot i5 :through v'vsrhieh a :high ltemperature .lhighvelocity gas iblast .fis discharged directly at :the rends fof :thesglass ibers its below ftlrefedge 123 tof :the block :22. The 5Y ihig'htemperatmze :ges :blast melts vthe `ends tof the y:bers :I9 :and theyelooity Lof 'the -blast muses `the :molten `glass from :each .of thebers 9 to :be rblonm lfrom :the end :of :the ber :and :simultaneouslytherewith .drawn into .a glass ,ber Lof extremely ine :diameter of onemicron oriless With the primary glass bers d'9 Lhaving a difametereoffrom :002 :to (M107 finch, -and `lnu'th the :high :temperature 'velocitygas :blast rhaving `-9.temperedure4oilll" linnnbigher;sind@l Lvelocity:uf 1BGD-2000 it./;sec., .glass bers :di :OLO to 110 zmicron z in:diameter :are Lproduced.

iBy controlling the diameter .of :the :primary :glassflber 9,1theirateotieedptemperaturerand welonity mi `,the :burner `gos at discharge slot:25, ith'e diameter of the drawn staple ber can 31e waited.

*Withitheiprimary 'glassifbers t9 being-Eediuni- :family finto :a burnerablast of .uniorm item'perature :and fvelccity, the sends of ztheprimary glass fibers :are all :rendered molten sat the rsame trete iwith:the mesult ithat fthe staple diber :blown ',irom the nds .of `theiprimary glass bers :is tot rrelau tively uniform length, as Well asbeingsuriiform iin diameter.

.Thus, znnder l controlled .'conditions, staple :ber :having aiiiameterof 'nnetmicnon mr iless canibe obtained i,with .fcontrolled iuniiormityof diameter 'nxrdglengthaoffthe stanlefber.

The rapparatus just :described feoniprsesn 'glass mbar formingLimit-.Awthatismlaced at Lone mf he paper forming-unit "i fAsimilar-:glass w'ber :forming lunit fC ds `placed prat :the @oppositeside of ithe paperforming aunit iBL 'i'lbus,1the dass :ber formingzunits .A :and C simulfdeaneously adeposit glass ,ber 1 of oneJ,-xnicron or -lcss on .thegpaperfformingunit .andffrombppositesidesthereof.

:of endless wireia-bric :belts 40 iamd -4.| 'If'herbelts :have adjacent.co-.extensive :runs i 42 and 43 and vthere "outer iruns 44 :and :45,respectively belt 140 Y:is :carried between f cylinders 46 :and :4:1seither auf :which :magy-tbe: suitablyfdrivenMhilezthe belt 41| carriedbetween the eylinslers 48 end yL9 either of 'which may e159 be-..driver1.. The bel-12S 4D and 4H ere dritten. et the saine lisserspeed whereby the adjacent ico-extensive 4 2 and f4.3 of ,the .beltsmore together between the cwespondine dryeeylinders.

Glass fiber :formed bif the `fiber termine A is deposited on the Aoutsrrun 44 of the :belt f4.0 while the g-less ber from the ber forming lC isdeposited `on the Outer 4519i the belt 4l, VThe outer mns .44 .and f4.5.0I the wire .rtafbric belts both move uupwardly as viewed :in mur-ei.

By moving the belts and il! et a Predetermined speed, glass ber issienesited .lon :the belts by the nuits A and C in 1a unifQrm .layerpredetermined thickness. ,Suction hambers 11 fand .5d ere providedadjacent the 'outer 44 fand 45 :of the belts `iin the area. of thedemstiol .of the ibers lon 4'the belts to lsecure more even distribntion of the ber zon the belts.

The `webs of :glass :ber deposited on the belts 40 .and 42| :are in arelatively loose zand deity 9.11- dition at the exposed face of each othe 'web s, `whereas the .tace :of the `webs that engage :the -belts 4,0sind 14:! are s, relatively densefsmonth :tace :as occasioned :by thedeposition of the fiber on :the belts that faireof 'a fine mesh.

'The loose ber faces =.0f the Webs :Bil land 150e, .that the louterexposed lffeices of the lwebs, :are brought :together .as the webs:passim/.er the upper cylinders 4K5 and 48. At the imctureiof'the .Webs60 and .60a they :are V`-Wet zwith `a liquid :from a spray head el.r:lhe liquid v-used may .be ,either Water or a suitable resin.

`With the loose bers -of fthe faees of `the Webs 'that arebroughtltogether met at the juncture .of `the faces, the 'loose fibers of thewebs interfelt into :a composite single web that then passes downwardlybetween the adjacent .cextensive runs 42 .and 43 of the belts All :andM.

As the .composite -AWeb moves .downwardly tbe- -ftween .the runs 42 and431of1the1wire tabrictbelts, the web is carried intoiaheatingchamber-.S5 ithat is provided .with fany suitable heating zmeans. Within:the Iheating chamber `there 'is iprovided :alseries of rolls (B6.against ytherun 42 :of thebelt :40 andithelcorresponding:seriesof4.rolls :61 against Athe run 43 of thebeltll. Theserolls y(it `and iii-Ixretain the runs l2 and :'43 #of the wire fabric belts iin`.predetermined space relationship to :compress vthe web carried:between Ithe :runs of :the 'belts :and `establish a. `web -o'f-predetermined thickness :dis-

charging from the 1heating lchamber b5 as -a .'dry -Web which is l:thenusable :as paper.

`The fnis'hed web 'Fm -is Wound `'into :a supply rollll.

I-f fdesired, the fglass bers deposited from the ber v"forming units nnndMC oanbe mois'tened Vwith :a suitable 'liquid kas :they areydeposited on theswire fabric fbelts 40 :and f4] :'from I.the spray`:heads s'lsla :and "Hb EE-his lprovides means for iplaeing additiveagents einto-glasszpaperformed -onithe apparatus, or :if desir-ed only:waiter 'may :be :prayed onto A:theibers torcondense VAthem .at this sune.

.Also, other -ber ftban glass `:ber can "be :added finto 'the rbaper :atvthe "time o'f forming the :Webs .60 andbuwrupon depositing ithe .ber onthe belts 'Maand :.41 simultaneously with ath'e deposition lof ttheglass bers. The radditive :bers cantierin- -troduced xthrough :suitable:blowers 1 2 rand T3.

iWhile the invention ,disclosed and :described herein :constitutes a:preferred .arrangement of zappratnsnndgmethodfof qperatingzthe same-yetmodifications can be made without departing from the spirit of theinvention, and those modifications that fall Within the scope of theappended claims are intended to be included here- 1n.

I claim:

1. A method of making glass paper that includes the steps of (a)establishing at least a pair of independent webs of glass bers, saidwebs consisting of glass bers of substantially uniform diameter andwhich range in diameter between about 0.04 and 1 micron and varying notmore than about i045 micron, said webs each having an exposed face ofglass fiber in relatively loose and fluffy condition, (b) moving saidwebs along to bring the corresponding exposed faces of each pair of webstogether, and (c) applying a wetting liquid onto at least one of saidpair of glass fiber webs while said webs are moving into coincidence tointerfelt said fibers at the said contacting faces and form a singlecomposite web of paper.

2. A method of making glass paper that includes the steps of (a)establishing at least a pair of independent webs of glass bers, saidwebs consisting of glass fibers of substantially uniform diameter andwhich range in diameter between about 0.04 and 1 micron Iand varying notmore than about i045 micron, said webs each having an exposed face ofglass ber in relatively loose and fluiTy condition, (b) moving said websalong to bring the corresponding exposed faces of each web together, and(c) applying a wetting liquid to at least one of said pair of webs asthey are moved along, and (d) thereafter heating the Webs to dry thesame and produce a single composite web of paper.

DOMINICK LABINO.

References Cited in the le 0f this patent UNITED STATES PATENTS NumberName Date 2,188,373 Pearce Jan. 30, 1940 2,382,290 Callander 1 Aug. 14,1945 2,489,242 Slayter et al Nov. 22, 1949 2,491,761 Parker et al Dec.20, 1949 2,564,882 Cubberley et al Aug. 21, 1951 2,571,334 Browne Oct,16, 1951

1. A METHOD OF MAKING GLASS PAPER THAT INCLUDES THE STEPS OF (A)ESTABLISHING AT LEAST A PAIR OF INDEPENDENT WEBS OF GLASS FIBERS, SAIDWEBS CONSISTING OF GLASS FIBERS OF SUBSTANTIALLY UNIFORM DIAMETER ANDWHICH RANGE IN DIAMETER BETWEEN ABOUT 0.04 AND 1 MICRON AND VARYING NTOMORE THAN ABOUT $0.45 MICRON, SAID WEBS EACH HAVING AN EXPOSED FACE OFGLASS FIBER IN RELATIVELY LOOSE AND FLUFFY CONDITION, (B) MOVING SAIDWEBS ALONG TO BRING THE CORRESPONDING EXPOSED FACES OF EACH PAIR OF WEBSTOGETHER, AND (C) APPLYING A WETTING LIQUID ONTO AT LEAST ONE OF SAIDPAIR OF GLASS FIBER WEBS WHILE SAID WEBS ARE MOVING INTO COINCIDENCE TOINTERFELT SAID FIBERS AT THE SAID CONTACTING FACES AND FORM A SINGLECOMPOSITE WEB OF PAPER.